The present invention relates to fluid valves and, more particularly, to a thermal fuel valve that undergoes a snap action upon opening or closing.
One type of thermal fuel valve is disclosed in U.S. Pat. No. 3,870,457, issued Mar. 11, 1975. Such a thermal fuel valve includes a container having an inlet and an outlet and a poppet that is moved by a heat warpable member between open and closed positions with respect to the outlet. As disclosed in the mentioned patent, the thermal fuel valve, for example, may be used with an electric igniter device in a gas range appliance or the like in order to control gas flow while the igniter provides automatic gas ignition at a gas burner without the need for a continuously burning, fuel wasting pilot light, thereby saving substantial amounts of fuel when the appliance is not in use. The electric igniter, which is positioned proximate a burner of such an appliance, and an electric heater, which is positioned in the thermal fuel valve to heat the heat warpable member therein, are desirably connected for series electric energization so that the thermal fuel valve will open and allow gas to flow to the burner only when the electric igniter has been energized and has achieved a suitable gas ignition temperature. The valve of such aforementioned U.S. patent also has provision for calibration to coordinate opening of the valve with the igniter temperature.
Since an appliance incorporating such a thermal fuel valve arrangement, as disclosed, for example, in the mentioned patent, does not experience any fuel flow in the fuel circuit between the appliance fuel input connection and the burner unless the thermal fuel valve is open, the pressure regulator in that fuel circuit which is usually located between the fuel input connection and the thermal fuel valve, may not operate properly to regulate the fuel pressure. While a satisfactory fuel flow to the pilot light in prior art ranges will maintain the pressure regulator operable, complete closure of fuel flow in ranges or the like in which no pilot lights are used may cause a relatively high pressure at the fuel valve under a no flow condition, which may impede valve opening.